Hydrocarbon-rich oils from subbituminous coal via facilitated hydrocracking over a tailored Zr@Co/C600 core-shell catalyst

The production of hydrocarbon-rich oil from low-rank coal via catalytic hydrocracking holds significant potential for applications in fuel production, chemical feedstock, and energy storage and conversion. However, enhancing the yield of derived oil while maximizing heteroatom removal to increase the proportion of hydrocarbons remains a major challenge. To address this, we developed a magnetic Zr@Co/C 600 catalyst with a core-shell structure, where ZIF-67-derived cobalt is uniformly dispersed on a nitrogen-doped porous carbon matrix as the core, and ZrO 2 serves as the protective shell. This catalyst exhibits a high specific surface area, well-defined mesoporous architecture, abundant acid sites (particularly strong acidic sites), and multiple active species containing nitrogen, oxygen, and cobalt. It demonstrates superior performance in cleaving >C–O– bridge bonds and removing heteroatoms. Moreover, the core-shell design effectively prevents the aggregation and leaching of active components, ensuring structural stability and sustained catalytic activity over five reuse cycles. DFT calculations reveal the energy barriers associated with the transition states of benzyloxybenzene reactions involving various active hydrogen species, offering theoretical support for elucidating the catalytic hydrogenation reaction mechanism. When applied to the catalytic hydrocracking of Xiwan subbituminous coal, the Zr@Co/C 600 catalyst increases the yield of soluble products from 10.4 wt% (non-catalytic) to 19.8 wt%. Furthermore, the relative contents of arenes and alkanes in the light oil fraction rise from 45.8% to 57.9% and from 20.5% to 23.0%, respectively, while those of arenols and other heteroatom-containing compounds decrease significantly.